My guest today is Mark Burnley, PhD from the University of Kent. He's studies endurance physiology, especially the power-duration relationship. For example, he was part of the group that first validated the 3-minute all-out test to estimate critical power. He's spent much of his career questioning why we can only maintain exercise when the intensity is less than 20-30% of our ability to generate force…why do we have so much additional capacity when we can't sustain it?